123 lines
4.3 KiB
Rust
123 lines
4.3 KiB
Rust
// A pass that annotates for each loops and functions with the free
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// variables that they contain.
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import syntax::print::pprust::path_to_str;
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import std::map::*;
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import option::*;
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import syntax::{ast, ast_util, visit};
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import syntax::ast::{serialize_span, deserialize_span};
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import syntax::codemap::span;
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export annotate_freevars;
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export freevar_map;
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export freevar_info;
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export freevar_entry, serialize_freevar_entry, deserialize_freevar_entry;
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export get_freevars;
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export has_freevars;
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// A vector of defs representing the free variables referred to in a function.
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// (The def_upvar will already have been stripped).
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#[auto_serialize]
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type freevar_entry = {
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def: ast::def, //< The variable being accessed free.
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span: span //< First span where it is accessed (there can be multiple)
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};
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type freevar_info = @~[@freevar_entry];
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type freevar_map = hashmap<ast::node_id, freevar_info>;
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// Searches through part of the AST for all references to locals or
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// upvars in this frame and returns the list of definition IDs thus found.
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// Since we want to be able to collect upvars in some arbitrary piece
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// of the AST, we take a walker function that we invoke with a visitor
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// in order to start the search.
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fn collect_freevars(def_map: resolve3::DefMap, blk: ast::blk)
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-> freevar_info {
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let seen = int_hash();
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let refs = @mut ~[];
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fn ignore_item(_i: @ast::item, &&_depth: int, _v: visit::vt<int>) { }
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let walk_expr = fn@(expr: @ast::expr, &&depth: int, v: visit::vt<int>) {
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match expr.node {
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ast::expr_fn(proto, decl, _, _) => {
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if proto != ast::proto_bare {
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visit::visit_expr(expr, depth + 1, v);
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}
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}
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ast::expr_fn_block(_, _, _) => {
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visit::visit_expr(expr, depth + 1, v);
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}
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ast::expr_path(path) => {
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let mut i = 0;
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match def_map.find(expr.id) {
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none => fail (~"Not found: " + path_to_str(path)),
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some(df) => {
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let mut def = df;
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while i < depth {
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match copy def {
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ast::def_upvar(_, inner, _) => { def = *inner; }
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_ => break
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}
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i += 1;
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}
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if i == depth { // Made it to end of loop
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let dnum = ast_util::def_id_of_def(def).node;
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if !seen.contains_key(dnum) {
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vec::push(*refs, @{def:def, span:expr.span});
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seen.insert(dnum, ());
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}
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}
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}
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}
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}
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_ => visit::visit_expr(expr, depth, v)
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}
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};
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let v = visit::mk_vt(@{visit_item: ignore_item, visit_expr: walk_expr
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with *visit::default_visitor()});
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v.visit_block(blk, 1, v);
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return @*refs;
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}
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// Build a map from every function and for-each body to a set of the
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// freevars contained in it. The implementation is not particularly
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// efficient as it fully recomputes the free variables at every
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// node of interest rather than building up the free variables in
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// one pass. This could be improved upon if it turns out to matter.
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fn annotate_freevars(def_map: resolve3::DefMap, crate: @ast::crate) ->
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freevar_map {
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let freevars = int_hash();
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let walk_fn = fn@(_fk: visit::fn_kind, _decl: ast::fn_decl,
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blk: ast::blk, _sp: span, nid: ast::node_id) {
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let vars = collect_freevars(def_map, blk);
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freevars.insert(nid, vars);
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};
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let visitor =
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visit::mk_simple_visitor(@{visit_fn: walk_fn
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with *visit::default_simple_visitor()});
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visit::visit_crate(*crate, (), visitor);
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return freevars;
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}
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fn get_freevars(tcx: ty::ctxt, fid: ast::node_id) -> freevar_info {
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match tcx.freevars.find(fid) {
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none => fail ~"get_freevars: " + int::str(fid) + ~" has no freevars",
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some(d) => return d
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}
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}
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fn has_freevars(tcx: ty::ctxt, fid: ast::node_id) -> bool {
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return vec::len(*get_freevars(tcx, fid)) != 0u;
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}
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// Local Variables:
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// mode: rust
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// fill-column: 78;
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// indent-tabs-mode: nil
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// c-basic-offset: 4
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// buffer-file-coding-system: utf-8-unix
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// End:
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